The present invention relates generally to machine elements and, more particularly, to pitmans and connecting rods.
It is difficult to produce oil and gas in an economic manner from low permeability reservoir rocks. Production rates are often boosted by resorting to hydraulic fracturing, a technique that increases rock permeability by opening channels through which reservoir fluids can flow to recovery wells. During hydraulic fracturing, a fluid is pumped into the earth under high pressure where it enters a reservoir rock and fractures it. Proppants are carried in suspension by the fluid into the fractures. When the pressure is released, the fractures partially close on the proppants leaving channels for oil and gas to flow.
Specialized pumps are used to develop the pressures necessary to complete a hydraulic fracturing procedure or xe2x80x9cfrac job.xe2x80x9d These pumps are usually provided with connecting rods that join a crosshead to a plunger that pressurizes a fluid. A conventional connecting rod is cast as a single unit and machined to desired tolerances. When portions of such a connecting rod wear out, the rod must be replaced in its entiretyxe2x80x94a time-consuming, wasteful and costly undertaking. Multi-piece connecting rods have been developed as a substitute for one-piece rods with the purpose of permitting just the worn portions of a rod to be removed. Unfortunately, multi-piece rods have not gained widespread acceptance since wear has tended to occur not only in the usual locations, but, also, at the junctions between the joined pieces. Thus, the known multi-piece connecting rods, like the one-piece rods they were meant to supplant, often require a full replacement when partially worn.
In light of the problems associated with the known connecting rods, it is a principal object of the invention to provide a new connecting rod with two portions that can be easily disconnected from one another for replacement when worn. Once disconnected from one another, a worn portion can be removed and replaced while the other portion remains in place in a pump, thus saving time and money. Disconnection can be accomplished with ordinary tools and with minimal training.
It is another object of the present invention to provide a connecting rod of the type described that has a solid, self-aligning connection between its two principal portions. Such a connection impedes wear where the two portions contact one another and ensures that set-up will be proper prior to use.
It is another object of the invention to provide a connecting rod of the type described whose principal portions are integrally formed. Lacking welds and other mechanical connectors, each rod portion is designed for maximum strength.
It is an object of the invention to provide improved elements and arrangements thereof in a connecting rod for the purposes described which is lightweight in construction, inexpensive to manufacture, and dependable in use. Although the connecting rod is described as being of particular utility in oilfield pumps, it is anticipated that it will provide like benefits in other reciprocating engines and machines.
Briefly, the connecting rod in accordance with this invention achieves the intended objects by featuring a tubular shaft with a cylindrical section and a gusset section whose wall thickness varies with length. A major flange projects from the outer end of the gusset section whereas a minor flange projects from the outer end of the cylindrical section. The major and minor flanges have holes for the passage of threaded fasteners. A link has an alignment plug for insertion into a socket in the outer end of the cylindrical section of the shaft. A ring is secured to the alignment plug. A number of threaded fasteners releasably join the shaft and the link.
The foregoing and other objects, features and advantages of the present invention will become readily apparent upon further review of the following detailed description of the preferred embodiment as illustrated in the accompanying drawings.